It is known in the art relating to vehicle engine exhaust catalytic converters for controlling exhaust emissions to provide a housing including an insulated cylindrical shell to which end cone assemblies are welded for connecting the converter to associated exhaust pipes or components. A catalytic element is assembled into the cylindrical shell prior to installing and welding the end cone assemblies on to the shell. The shell may have a circular cross section or be of any suitable non-circular configuration.
FIG. 1 shows in cross section part of a prior catalytic converter including a housing 10 having a non-circular cylindrical shell 12 enclosing an insulating pad 13 wrapped around a catalytic element 14 of any suitable type. The shell 12 is connected at both ends (only one end being shown) with an end cone assembly 16 of known construction, best shown in FIG. 2. An adapter 18 is inserted in and welded to an outer end 20 of the end cone assembly.
The end cone assembly 16 includes a formed sheet metal outer cone 22 and a smaller formed sheet metal inner cone 24 with a fibrous insulating pad 26 between them to form the insulated dual wall cone assembly 16.
The outer cone 22 includes an outer large end 28 that is generally cylindrical and sized to slide over one end of the converter shell 12. A slight outward flare 30 is provided at the free edge of the outer large end 28 to assist the installation. The outer large end 28 connects with a generally conical outer wall 32 leading to an outer small end 34 which again is generally cylindrical but of preferably circular cross section.
The inner cone 24 also includes an inner large end 36 that is generally cylindrical and sized to fit within the same end of the converter shell 12. A slight outward flare 38 at the free edge of the inner large end 36 engages the insulating pad 13 within the shell 12. The inner large end 36 connects with a generally conical inner wall 40 leading to an inner small end 42 which again is generally cylindrical but of preferably circular cross section. The inner small end 42 is sized to fit closely within the outer small end 34 of the outer cone 22 so that these ends 34, 42 engage one another. To maintain the parts in assembly, dimples 44 may be formed in the engaged small ends 34, 42. In the illustrated embodiment, the inside diameter of the small end 42 is about 2.5 in. (63.5 mm) in order to connect with exhaust pipes of about 2.5 in. outer diameter.
The conical outer and inner walls 32, 40 of the assembly 16 are spaced apart to define an insulating space in which is disposed the preferably fibrous insulating pad 26. Other forms of high temperature insulation may also be used. The pad 26 is preferably installed on the inner cone 24 before inserting it into the outer cone 22 to form the end cone assembly 16.
Finished end cone assemblies 16 are installed on both ends of the converter shell 12 after assembly of the wrapped catalytic element 14 into the shell 12. The end flares 30 of the outer cones are then welded to the outside of the shell 12 to hold the end cone assemblies 16 in place and seal the joints against gas leakage.
In the prior embodiment of FIG. 1, the end cone assembly 16 is shown connected with the adapter 18 which is inserted into the inner small end 42 of the assembly and welded around the joint to make it gas tight. If desired, other forms of exhaust pipe connections could be attached to the end cone assembly.
The outer and inner cones 22, 24 of the assembly 16 are each formed by a seven step sheet metal forming process including steps of blanking, drawing (three steps), restrike, piercing and extruding. Thus one set of seven transfer dies are required for the production of each cone. Previously, when a larger or smaller pipe connection opening was required to connect with larger or smaller exhaust pipes, the illustrated assembly was designed with completely new outer and inner cones. This required provision of two new sets of dies, seven dies per set for each cone, and complete change out of all the dies whenever a production change between smaller and larger opening cone assemblies was required, all involving considerable time and expense. The same situation exists for end cones produced by progressive dies.